Conversely, if the same companion desert also applies to lower-mass stars, which are believed to form in a similar manner, we expect that they should host a substantial fraction of brown dwarf companions, corresponding to \(q\approx 0.1\) –0.5 mass ratios. A few such systems have already been identified , [1]}, [2]} although their statistical analysis is affected by the generally old (and often highly uncertain) age of M dwarfs, which leads to substellar companions being extremely faint. The occurrence rate of such companions is still an open question being actively investigated [3]}, [4]}, [5]}, [6]}. At shorter separation, giant planets (and by extension brown dwarfs) are much rarer than among solar-type stars [7]}, in line with the trend we predict at wider separations. At the other extreme, the presence of a gap in the distribution of (stellar) companions remains to be determined [8]} and is complicated by the large distance and extreme contrast between primary and companion stars. Besides, it is likely that the formation of massive stars involves more complex processes and therefore, the presence of a universal mass ratio gap for low-mass up to intermediate-mass stars does not guarantee that it should apply at for the highest mass stars.
